As I mentioned in my previous studies, a few existing vaccines may have some kind of protection against COVID-19 related deaths. For instance, several scientists researched and tried to determine the long-term impact of BCG or Polio vaccines on human immune system. In this my study I continue to review the correlations of many of existing vaccines used in the world's countries with the COVID-19 deaths per capita in each of those countries. A few vaccines came to my attention - mostly because I see the negative correlation between vaccine percent of coverage in specific country and death rate per capita in the same country, meaning that those vaccines may have some kind of protective effect against COVID-19 related deaths.
One of such vaccine is called JapEnc (Japanese encephalitis): it was developed to prevent Japanese encephalitis virus, the most important cause of epidemic arbovirus encephalitis in Asia, that has a wide clinical spectrum ranging from asymptomatic infection to severe infection with permanent neurologic sequelae and a high case fatality rate of 30 to 70%. JapEnc vaccine is a formalin-inactivated virus derived from purified infected mouse brain. Immunogenicity studies in the United States indicate that three doses are needed to provide protective concentrations of antibody in more than 80% of vaccinees. The JE vaccine is recommended for persons who will be residing in areas where JE is endemic or epidemic (80). Despite the high fatality rate, vaccine has not been available in the United States until recently. In December 1992, a JE virus vaccine was licensed in the United States for use in persons living in or traveling to Asia.
Another vaccine which percent of coverage has a negative correlation with the COVID-19 death rate is the Diphtheria containing vaccine (DiphCV6). Diphtheria primarily infects the throat and upper airways and is fatal in 5 – 10% of cases. Although many countries has this vaccine mandated for children under the age 5 - in Europe only one country (Bulgaria) has DiphCV6 mandated for age over 25 (including age over 65).
And the third vaccine that may have some impact on COVID-19 related deaths is the Human Papillomavirus vaccine (HPVfem, HPVmale) which was developed for primary prevention of cervical cancer and other HPV-associated diseases. It is estimated that the vaccines may prevent 70% of cervical cancer, 80% of anal cancer, 60% of vaginal cancer, 40% of vulvar cancer and possibly some mouth cancer. In Europe, it is mandatory in a few countries (Greece, Macedonia) as well as in a few countries in Asia and Africa. In USA only two states have such vaccine as mandatory.
An example of strong positive correlation between percent of coverage and COVID-19 death rate is the DTP vaccine (shown on the same worksheet as JapEnc). This is combined vaccine for Diphtheria, tetanus, and pertussis which are all bacterial diseases and a combination vaccine against all three diseases is commonly used.
To conclude: the correlation we see doesn't mean a causation, so it will be incorrect to to suggest that vaccines mentioned above (JapEnc, DiphCV6, HPVfem/HPVmale) have direct impact on COVID-19 related mortality (i.e. may serve as some kind of protection). But ongoing scientific researches may discover such dependencies and come up with recommendations.